Mobile telephones often have various sensing modalities, such as global positioning service (GPS) receivers, microphones, compasses, accelerometers, cameras, and others. Some mobile device applications utilize these sensing modalities to perform various functions, such as to identify the location of the mobile device on a map or to determine nearby points of interest such as restaurants or shops. Over-usage of sensors can be a drain on battery resources or other resources such as processor throughput. Also, some mobile device applications are hosted by a cloud computing service, requiring that sensor data be uploaded to an application server somewhere on the cloud. This raises privacy concerns as well as issues of network bandwidth usage for a user of the mobile device. Also, application developers might be interested in utilizing mobile device sensor data from a large number of devices, but lack either access to the critical mass of mobile devices needed to implement the desired functionality, or lack the resources to utilize a large amount of mobile telephone data.